Charles w



(No Model.)

C. W. DREW & B. R. FRANCIS. ELECTRIC HEATER.

No. 439,724. Patented Nov. 4, 1890.

9371211355525- Jzzv-s niazt M 5.7222175: I471. 171-5- and I :12? 15 0L m. Inward UNITED STATES PATENT OFFICE.

CHARLES \V. DREWV AND EDWARD R. FRANCIS, OF MINNEAPOLIS, MIN- NESOTA.

ELECTRlC HEATER.

SPECIFICATION forming part of Letters Patent No. 439,724, dated November 4, 1890.

Application filed February 20, 1890. Serial No, 341,177. (No model.)

To all whom it may concern.-

Be it known that we, CHARLES WV. DREW and EDWARD R. FRANCIS, both of Minneapolis, in the county of Hennepin and State of Minnesota, have invented certain Improvements in Electric Heaters, of which the following is a-specification.

The object of this invention is to provide improved means for utilizing an electric current for heating purposes; and to this end the invention consists, generally, in providing within a suitable casing an electrical resistance consisting of a series of sticks or rods of carbon, graphite, or graphitized material mounted in suitable conducting-blocks that are insulated from each other, whereby the electric current passes through all of the electric resistance.

The invention further consists in the arrangement of the electrical resistance in an air-tight casing, which prevents oxidation of the material forming the resistance.

The invention further consists in the means for supporting the electrical resistance, so as to permit an expansion or contraction of the rod forming such resistance.

The invention further consists in the construction and combination hereinafter described, and particularly pointed out in the claims.

In the accompanying drawings, forming a part of this specification, Figure 1 is a plan view of our improved device. Fig. 2 is a section on line a; m of Fig. 1, with the cover or heating-plate in position.

In the drawings, 2 represents a suitable casing, which may be of any desired form or construction, and which may be made of any suitable material. This casing is preferably provided with a suitable lining 3 of insulating and non-heat-conducting material, which forms the base upon which the resistance materials are supported. Arranged within the casing is a series of sticks or rods 5, composed, preferably, of carbon, graphite, or graphitized material. These sticks are preferably arranged parallel with each other with their ends supported in blocks '7, formed of any suitable electric conducting material. The blocks '7 are secured within the casing and insulated from each other. Each block is preferably arranged to receive the ends of two of the carbon-rods and the blocks are arranged in alternating series, so that while any block supports the ends of two of the sticks the opposite ends of such sticks or rods are supported in difierent blocks. A suitable electric wire or conductor 9 is connected to the first block at each end of the heater. As each block is formed of a suitable conductor, which ofiers little resistance to the current, it forms a connection between the ends of the rods supported by it. An electric current being passed through one of the wires 9 will be caused to traverse the heater, passing back and forth through the resistance-rods, whereby as said current passes through said rods a large amount of heat is radiated therefrom. A suitable heating-plate 11 is arranged over the resistance-rods and forms, preferably, the top or facing of the casing. This plate is preferably arranged near to the resistancerods, so that the heat radiated from said rods causes said plate to be raised to a high temperature.

The blocks 7 are preferably provided with openings or perforations, through which extend studs or rods 10, which are preferably insulated from said blocks, one end being secured to the insulating-lining of the casing. By this means the metallic blocks '7 are secured in position, so as to be capable of moving to allow for the expansion and contraction of the rods of the resistance material.

For the purpose of preventing oxidation of the resistance-rods within the casing we prefer to make the casing air-tight. This may be done by making the plate 11 fit with an air-tight joint upon the casing.

It will be seen that this heater is exceedingly simple in construction, that the resistance-rods of carbon or graphitized material are supported therein so as to be capable of expansion and contraction, and that as the current passes through all of the resistancerods a large amount of heat will be radiated therefrom.

We claim as our invention The combination, in an electric heater, with a suitable casing, of an electric insulating and non-heat-conducting base, electrical resistance consisting of rods or strips of carbon,

graphite, or graphitized material, a series "of Inv testimony whereofi we haye hereunto set blocks of electric conducting in'ettel 'i al pro} on!" hands this 15th day of Februar 1890. vided with perforations, into which the ends CHARLES W DREW of said rods en strips are inserted, end rods EDWARD FRANO'IS 5 secured to sald base upon which said blocks are independently movable, so as to allow for In prgasenceofthe expansion or contraction of Sztid red in- V A. M. GASKET dependently, substantially as described. S. W. ROBERTS. 

